This one's pretty cool: the cover of Are A Drag is a parody of a painting by Cassius Marcellus Coolidge named Waterloo, which depicts dogs playing poker.

In Coolidge's Waterloo, two paintings appear in the background. In their adaptation, the Gimmes used Waterloo and another one of Coolidge's paintings about gambling dogs:

Poker Sympathy by C. M. Coolidge

Are A Drag is the Gimmes' gayest album: Over The Rainbow? Tomorrow? Come on, how gay is that? The cover had to reflect that so the drunketeers got all dressed up and each one of them became a character from a musical that appears on the album: Chris is a sexy lady from A Chorus Line, Joey is Annie from Annie, Dave is Dorothy from The Wizard Of Oz, Mike is Sandy from Grease, and Spike is Dr. Frank-N-Furter from The Rocky Horror Picture Show.

The source of the back cover hasn't been identified yet... It's probably just a random collage.